归并排序(2-路)

来源：互联网发布：数据库王珊第5版答案编辑：程序博客网时间：2024/05/17 07:18

核心代码：

/*将相邻的有序区间SR[i...m]和SR[m+1,n]归并为有序的TR[i...n]*/void Merge(RcdType SR[], RcdType TR[], int i, int m, int n){int j, k;for (j = m + 1, k = i; i <= m && j <= n; k++) {if (SR[i].key <= SR[j].key) {//'<='改为'<'排序会变不稳定TR[k].key = SR[i++].key;}else TR[k].key = SR[j++].key;}while (i <= m) TR[k++].key = SR[i++].key;while (j <= n) TR[k++].key = SR[j++].key;}/*R1,R2交替归并*/void MergeSort(RcdType R1[], RcdType R2[], int i, int s, int t){/*i%2 == 1 R1归并排序到R2*/int m;if (s == t) {if (i % 2 == 1)R2[s] = R1[s];//单个元素直接复制过去}else {m = (s + t) / 2;MergeSort(R1, R2, i + 1, s, m);MergeSort(R1, R2, i + 1, m + 1, t);if (i % 2 == 1) Merge(R1, R2, s, m, t);else Merge(R2, R1, s, m, t);}}

测试代码：

#include <stdio.h>#include <stdlib.h>#include "data_structure.h"#include "msort.h"Status InitRcdList(RcdList &L, KeyType key[], int n){if (n <= 0)  return ERROR;L.rcd = (RcdType*)malloc((n + 1)*sizeof(RcdType));if (L.rcd == NULL)  return ERROR;L.length = n;for (int i = 1; i <= n; i++)L.rcd[i].key = key[i - 1];return OK;}void PrintRcdList(RcdList list){for (int i = 1; i <= list.length; i++)printf("%d ", list.rcd[i].key);printf("\n");}int main(){RcdList list;KeyType key[7] = { 42, 30, 68, 98, 86, 15, 57 };InitRcdList(list, key, 7);PrintRcdList(list);RcdType *R;R = (RcdType*)malloc((list.length + 1)*sizeof(RcdType));MergeSort(list.rcd, R, 0, 1, list.length);PrintRcdList(list);system("pause");return 0;}

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